Swing frame grinding machine



May 15, 1934. H w. DUNBAR SWING FRAME GRINDING MACHINE Filed March 16,1929 2 Sheets-Sheet l :8 O O o O gwuemtoz HOWARD WDUNBFIR mm hm mm mmalike cum:

WITNESSES W flu y 1934- H. w. DUNBAR 1,958,534

SWING FRAME GRINDING MACHINE Filed March 16. 1929 2 Sheets-Shet 2 Fig. 4

gwuewtoz MTNESSES HOWHH'D W DUNBHR Patented May 15, 1934 UNETED STATESPATENT OFFICE SWING FRAME GRINDING MACHINE Application March 16, 1929,Serial No. 347,558

4 Claims.

This invention relates to grinding machines and more particularly to aswing frame grinding machine adapted for use in snagging or grindinglarge irregular surfaces.

Swing frame grinding machines have been in common use in founderies andsimilar manufacturing plants for use in the grinding of billets,snagging and cleaning large, heavy castings and similar work which aretoo massive in size and weight and too irregular in contour foreflicient grinding on a floor stand. Machines heretofore in productionuse have had several disadvantages which impaired the efficiency of thegrinding operation as well as caused considerable fatigue and aconsequent drop in eficiency of the operator as the working dayprogressed. Previous swing frame grinding machines have been excessivein weight so that the operator had to swing a massive structure as thewheel was passed across the surface of the object being ground; thewheel end of the structure was provided in most cases with overhangingand projecting bearing and driving members which materially obstructedthe operators visibility of the work being ground.

In numerous of these previous constructions, the belt drive has beenprovided on one side of the frame or a rotary shaft through the framesupporting the machines. These drives have not been wholly satisfactory,since the belt drive on one side is of necessity of considerable widthto produce the proper driving friction to rotate the wheel and obstructsthe operators vision of the work being ground and in addition tends tobring the rotary driving thrust wholly on one side of the wheel.

It is one object of this invention to overcome these numerousdifficulties and to provide a swing frame grinding machine having anarrow wheel head construction which does not seriously obstruct theoperators view of the work being ground.

Another object of this invention is to provide a driving belt on eachside of the grinding wheel so that a uniform, steady and efficient driveby a narrow V-type of belt on each side of the wheel may be obtained.This type of driving belt offers the maximum driving efficiency with aminimum obstruction of the operators view of the work.

A further object of this invention is to provide a suitable mounting forthe driving motor so that the motor may be readily adjusted to tensionthe driving belt and also to permit changing the driving belt from a setof pulleys of one diameter to a set of pulleys having a smaller diameterto permit varying the speed of rotation of the wheel and at the sametime to tension the driving belt for either speed.

It is a still further object of this invention to provide a suitablebearing support in which the bearings for rotatably supporting thegrinding wheel are wholly within the center aperture of the grindingwheel thereby producing a compact, unitary mounting for the grindingwheel which produces a very narrow wheel head construction and reducesthe obstruction of the operators vision to a minimum.

It is a still further object to provide a readily accessible meanswhereby the grinding wheel may be removed-from its support when thewheel becomes worn to permit the operator to change the wheel and toinsert a new wheel thereinstead.

It is a further object to provide driving pulleys on either side of thegrinding wheel which are preferably formed as integral portions of thewheel clamping flanges so as to reduce the width of the wheel mountingand its driving means to a.

minimum.

With these and other objects in view as will be apparent to one skilledin the art, this invention resides in the combination of parts set forthin the specification and covered by the claims appended hereto.

Referring to the drawings illustrating one embodiment of this inventionand in which like reference numerals indicate like parts:

Fig. 1 is a side elevation of a swing frame grinding machine having aportion of the belt guard broken away to show the motor and the belttightening device;

Fig. 2 is a plan view of the machine;

Fig. 3 is a cross sectional view on an enlarged scale takenapproximately on line 3-3 of Fig. 1 having the upper portion of thewheel guard broken away and showing the bearing and spindle mount forthe grinding wheel;

Fig. 4 is a sectional View taken approximately on the line 4:*-4: ofFig. 2 showing the motor support with the belt guard removed;

Fig. 5 is a fragmentary side elevation of the grinding wheel head,showing the wheel partly removed;

Fig. 6 is a fragmentary side elevation showing the motor support andbelt tightening toggle in operating position; and

Fig. 7 is similar to Fig. 6 with the toggle in an open position and themotor swung toward the frame.

In accordance with this invention, a swing frame grinding machine maycomprise a frame adapted to be suitably suspended by a flexible overheadsupport, a motor mounted on one end of the frame, and a grinding wheelremovably supported on the other end of the frame and driving beltconnections between the motor and wheel. A handle is attached to theframe near the grinding wheel whereby the operator may move the wheelback and forth across the piece of work to be ground. In order toprovide the maximum visibility, the wheel is driven by narrow belts,such as V-belts, and to give a steady and efficient drive, a belt isarranged on each side of the wheel. A narrow grinding wheel may be usedand the driving pulleys be positioned adjacent to the opposite sidefaces of the grinding wheel, and the motor may be provided with drivingpulleys on one end of its shaft which are properly aligned with thewheel pulleys. The wheel is preferably mounted on a non-rotatable arborremovably mounted in the frame and supported by means of roller bearingson this arbor, the parts being so arranged that by removing thenonn'otatable arbor, the wheel may be withdrawn from between the sidesof the protective wheel guard within which it is mounted. A furtherfeature of the invention involves combining the wheel flanges whichsecure the wheel on its rotatable support with the driving pulleys, toeconomize space and avoid the use of wide parts which obstruct thevision of the operator. Also the motor is adjustably mounted on theframe, and preferably by means of a pivotal support and a togglepositioning device, that the driving belts may be readily loosened forreplacement of the wheel without altering the belt tensioningadjustment.

Referring more particularly to the drawings which illustrate oneembodiment of this invention, a main frame 10 of tubular form supports amotor 11 at one end and a rotatable grinding wheel 12 at the other. Thegrinding wheel is removably mounted within a wheel guard formed of twoside plates 14 and 15 suitably connected to a peripheral guard strip 16bent in a partial cylindrical form to cover the upper portion of thegrinding wheel and leave the lower portion exposed for contact with thework. This whee-l guard is secured to the tubular frame 10 by suitablemeans which, as illustrated, may comprise a socketed member 18 havingflanged projections 19 bolted to the side plates 14 and 15 of the guard.The end of the tubular member 10 is inserted into the socket andsuitably fastened in place. The outer end of the wheel guard carries ahandle 20 suitably secured thereto, whereby the operator may move thegrinding wheel over the work as desired.

The member 18 is provided with an upstanding eye 21 arranged forengagement with a hook or other securing device. A socketed member 22 ismounted on the opposite end of the frame and is provided with an eye 23for the insertion of a hook from an overhead support. The eye members 21and 23 permit what is termed double suspension, in which case the motorend of the swinging frame is rigidly held from the ceiling by a flexiblesupport, such as a rope or cable, while the wheel head end is supportedby a coun 'terweighted rope running over pulleys.

It is desirable in most instances that the entire frame be suspendedfrom a single support at the center and be properly balanced so thatthe: operator may without undue exertion readily swing the frame in anydirection. A suitable balancing device is provided comprising a sleeve25 which is rotatably mounted on the central portion of the framebetween the fixed collars 26 and 27. This sleeve has a flange 28provided with holes for the insertion of a tool used to turn the sleeve.The peripheral face of the sleeve is screw threaded and engages acorrespondingly threaded aperture in a supporting member 29 having aneye 30 by which the machine may be suspended by any suitable flexiblesupport. It will thus be seen that the sleeve 25 may be rotated withinthe supporting member 29 to position the latter at the center of gravityof the machine. The threaded portion of the member 29 is split andarranged so that the ends may be clamped by means of a cap screw 32 tolock the member in in any desired position relative to the threadedsleeve. This balancing device enables the operator to maintain themachine in proper balance to compensate for the loss of weight at oneend due to grinding wheel wear.

The socketed member 22 is mounted on the main frame member 10 and issloped downwardly to provide a support for the motor so that the mainframe 10 is substantially parallel with the belt run. The electric motor11, which may be of any standard construction, is mounted upon bearingblocks 35 which are pivoted to the lower end of member 22.

A suitable linkage mechanism, such as a toggle joint is provided forholding the motor in one of two adjusted positions, as shown in Figs. 6and 7. The forward part of the motor 11 is supported by a yoke member orbracket 37 secured to the motor nd pivotally connected by a pin 38 to alocking member 39. the locking member 39 at one end, and to an eye boltil at the other end. The eye bolt 41 is rigidly held by two nuts to arocker member 42. This member 42 is formed with a flat elongated headand a stud extending therefrom which is rotatably mounted in a hole inthe member 22 and fastened in place by a nut 4:6. The locking member 39is provided with a socket in its outer end in which a bar or convenienthandle may be inserted, to give the operator suihcient leverage to rockthe member 39 without excessive effort. member 39 has a lug 43 whichengages the side of the link and so definitely limits its movement inone direction. An eye bolt 44 is pivotally' mounted upon the pin 38, andits lower end is siidably supported in an elongated slot 45 in the headof the rocker member 42. Two nuts 47 are threaded onto the lower end ofthe eye bolt 44 to enable the operator to adjust the effective length ofthe bolt to aid in maintaining the toggle in a locked position when theycontact with the member 42.

When it is desired to relieve the tension on the driving belts, theoperator inserts a bar or handle in the socket of the locking member 39and rocks A link so is pivotally connected to v The locking the latterupwardly whereupon the toggle folds up and motor 11 rocks downwardlyabout its bearing blocks 35 from the position shown in Fig. 6 to thatshown in Fig. 7. Conversely, when it is desired to lock the motor in aposition with the belts under a driving tension, as shown in Figs. 1 and6, the operator rocks thelocking member 39 downwardly until its motionis limited by the lug 43 contacting with the link 40 and by the nuts 47on the eye bolt 44 contacting with the under side of the rocking member42, thereby preventing further motion of the toggle. Proper belt tensiongoverned by the adjustment of the nuts upon the eye bolts 41 and 44.

One feature of this invention comprises a peculiar mounting for thegrinding wheel permitting it to be readily removed from the wheel guardwhich is rigidly fixed on the frame of the machine. To this end, thewheel is mounted on a bearing unit located wholly between the sides 14and 15 of the Wheel guard and which in turn is supported on an arborcarried by the sides of the wheel guard. A further feature involves thecombination of the flanges which support the wheel on its opposite sideswith the pulleys which carry the driving belt. As illustrated in Fig. 3,the wheel center or hub 50 is provided with an integral flange 51 toengage and support one side of the wheel 12; and a removable flange 52engaging the other side of the wheel which is adjustably fastened to thewheel center by means of a series of cap screws 55. The wheel center 50has a reduced end portion 56 which serves to support and locate theclamping flange 52. The Wheel center 50 fits within the central apertureof the grinding wheel and the clamping flange 52 coacting with the fixedflange 51 securely clamps against faces of the wheel to hold it securelyon the center.

The assembled wheel center unit is removably supported on the guard bymeans of an arbor 60 which passes through the center of the wheel and isremovably secured to the side plates 14 and 15 of the wheel guard orhousing. The arbor 6O is supported by the bushings 61 and 62 which are66 at the other end of the arbor serve to lock the arbor in position.The key 66 is tapered and passes through a tapered slot in the arbor andmay be driven into place to lock the arbor rigidly in position.

A sleeve 67 is mounted on the arbor 60 between the ends of the bushings61 and 62, and is secured against rotation by a key 70 mounted in thearbor and engaging keyways in the bushing 61 and the sleeve 67. Thissleeve has a central raised portion 71 forming two shoulders whichlocate the inner members '73 and '74 of two roller bearings. The members'73 and '74 are locked in position by collars '7 6 and 77 which arethreaded onto the reduced ends of the sleeve '71 and may be pinnedthereto, if desired. The sets of rollers 78 and 79 3 of the two bearingswhich ride on the race-ways of the inner members 73 and 74 in turnsupport the outer bearing race rings 81 and 82. These rings aresupported in a central aperture in the wheel center 50 and are held inposition by an inwardly projecting flange 85 of the wheel center on oneside and a removable ring 86 on the other side which is secured by capscrew 87 to the wheel center. It will, therefore, be seen that thegrinding wheel is mounted on roller bearings located within the centerhole of the wheel, and

. that these roller bearings are carried by a nonrotatable arbor whichis removably supported by the side plates of the wheel guard. A worn-outwheel may be readily replaced by opening the toggle joint supporting themotor, removing the driving belts from the motor pulleys, then removingkey 66 and removing the arbor 60 whereupon the wheel and its bearingsupport will drop downwardly from the wheel guard, as indicated in Fig.5. The clamping flange 52 is then removed from the wheel center 50 andthe wheel may then be removed therefrom without disturbing theadjustment of the bearings.

One of the important features of this invention,

' as above explained, is that the wheel bearings are so arranged andconstructed as not to seriously interfere with the operators visibilityof the work beneath the wheel. Hence, it is preferable to use a narrowdrive belt which may be round or substantially V-shaped. As illustrated,a V-belt is provided which engages correspondingly V- shaped grooves inthe pulleys. In order that the wheel pulleys may not obstruct the viewof the operator, they are preferably formed as integral parts of thewheel clamping flanges. I-Ience, as illustrated, substantially V-shapedgrooves 90 and 91 are formed in the clamping flanges 51 and 52respectively. The belts 93 and 94 pass through openings 95 in the Wheelguard and engage the pulley grooves 90 and 91 respectively.

It is desirable in a grinding machine of this type to provide means forincreasing the speed of the wheel as it wears away. To accomplish this,a grooved pulley 92 having a plurality of pairs of spaced pulley groovesis mounted on the end of the motor shaft 96. This pulley is providedwith two pairs of grooves 97 and 98 of different diameters, which arespaced to correspond with pulley grooves 90 and 91 on wheel flanges 51and 52, so that each of the belts may be run on the larger pulleygrooves 97 or on the smaller diameter grooves 98 as desired. Normallythe belts run in the smaller pulley grooves but when the wheel is worndown to a considerable extent, the pulley may be removed from the motorspindle and reversed, end for end, so as to align the grooves of largerdiameter with the pulley grooves 90 and 91 of the grinding wheel.

A belt guard 100 is provided to enclose the lower runs of the drivingbelts 93 and 94. This guard is fastened at one end to the member 22 by astud 101 and at the other end by screws 102 to the lower part of thewheel guard.

The operation of this machine will be apparent from the followingdisclosure. A grinding wheel 12 is mounted on the wheel center 50, theclamping flange 52 is then secured in place by means of the screw 55 andthe assembled wheel unit then inserted within the wheel guard with thebelts 93 and 94 engaging the pulley grooves 90 and 91. When the wheel isinserted in this position between the plates 14 and 15 of the wheelguard, the supporting stud 60 is inserted and locked in place by the key66. The other ends of the driving belts 93 and 94 are put in place oneither pair of grooves 97 or 98 on the driving pulley 92 which is keyedto the motor shaft 90. As previously explained, either pair of pulleysmay be aligned with the pulley grooves 90 and 91 depending upon thespeed of rotation desired for the grinding wheel. After the belts havebeen positioned, the operator inserts a bar in the socket 39 and movesthe bar downwardly which closes the toggle joint and swings the motorinto operating position which properly tensions the driving belt. Afterthis operation has been completed the operator then by slackening-off onthe clamping screw 32 may rotate the threaded bushing 25 to balance themachine. When this is accomplished, the machine is ready for use and theoperator by manipulating a suitable starting control may start the motorand set the grinding wheel in rotation ready for use in grinding. As thegrinding wheel wears away the wheel head end of the machine will becomelighter and the center of gravity changes so that the machine is out ofbalance. time to time as desired by turning the threaded sleeve 25 toadjust the fulcrum point of the machine. If desired to change the speedof the The operator may correct this from the bearings.

grinding wheel, the operator may open the toggle connections and slackthe belt and then reverse the pulley 92 to position the other set ofpulley grooves 98 into alignment with the pulley grooves 90 and 91 onthe wheel mounting. The motor may then be swung into operating positionby closing the toggle and if necessary, due to the change in diameter ofpulley sizes, the slack in the driving belts may be taken up byreadjustment of the nut on the eye bolts 41 and 44.

It will be appreciated that this construction provides a swing framegrinding machine which may be easily moved over a piece of work ofirregular surface contour and that the operator may readily see the workfrom his position near the handle of the machine, owing to the fact thatthe wheel guard is not much wider than the grinding wheel and that thebearings do not overhang the sides of the guard and the wheel pulleysare close to'the wheel and the belts are narrow. The machine, owing tothe type of bearings provided, is capable of being used at high speedsand the belt drive to the wheel is sure and steady, there being amplefrictional contact between the V-shaped belts and the V-grooves of thetwo wheel pulleys to drive the wheel under a heavy load. The belt isautomatically maintained tight owing to the weight of the motor pullingback against the belt. The wheel may be rotated at either of two desiredspeeds depending on the wishes of the operator, as determined ordinarilyby the size of the wheel; and it is feasible to shift the belt from thesmaller to the larger pulley without changing the pulley block on themotor shaft, but depending on the sides of the pulley to hold the beltin position, although if desired the pulley may be reversed end for endto properly align the grooves thereof with the wheel pulleys. The togglejoint, which serves to move and to lock the motor in position, is veryeasily manipulated and adjusted. The frame and the accessories thereonform a light body which may be easily moved by the operator and swungfrom one position to another and it may be readily balanced and handledas desired. It is easy to remove the wheel from the frame withoutdisturbing the adjustment of the bearings. All that is required is towithdraw the center arbor and permit the wheel to fall out after thebelt has been loosened. When a new wheel has been mounted on the center,then the assembled parts are lifted into the wheel housing and fastenedthere. They are then ready for use without any adjustment of Numerousother advantages will be readily apparent to one who is familiar withthis art.

Having thus described the invention, what is claimed as new and desiredto secure by Letters Patent is:

1. A swing frame grinding machine comprising a frame, a grinding wheelrotatably mounted on one end thereof, a motor, a motor support pivotallymounted on the other end of said frame, driving belt connections betweenthe grinding wheel and the motor, a device to adjustably regulate thetension of said driving belt, and a toggle mechanism arranged to swingthe motor to release the driving connections without altering theadjustment of the belt tensioning device.

2. A swing frame grinding machine comprising a frame, a motor adjustablymounted on one end of the frame, a grinding wheel rotatably mounted onthe other end of said frame, a narrow V-type driving pulley on each sideof the grinding wheel and located closely adjacent thereto, a drivingshaft projecting. from said motor, a pulley on said shaft having twopairs of narrow v-type grooves of different diameters, said pulley beingmovable to align either pair of said grooves with the wheel pulleys, apair of belts connecting the wheel pulleys and the motor pulley, meansfor pivotally adjusting the position of said motor to adjust the tensionof the driving belts when engaging either pair of pulley grooves, and adevice for quickly releasing the belt tension without altering the belttension adjustment. 7

3. A swing frame grinding machine comprising a frame having a centralsuspension support, a wheel guard supported on the frame which hasspaced side plates, a handle on the wheel guard end of the machine forguiding the wheel over the work, a grinding wheel spindle supportedsolely by the side plates, a grinding wheel rotatably mounted thereonbetween and close to the side plates, a pulley close to each side of thewheel winch has a narrow pulley groove, a motor mounted on the oppositeend of the frame and 105 arranged to counterbalance the wheel, pulleyson the motor shaft having narrow grooves aligned with the wheel pulleys,and a narrow belt on each side of the grinding wheel connecting themotor pulley with the wheel pulley, said belts, wheel mount and wheelpulleys being located substantially within the planes defined by thesides of the wheel guard plates, whereby obstruction of the operatorsview of the work being ground is minimized.

4. A swing frame grinding machine comprising a frame, a longitudinallyadjustable suspension. support located substantially centrally thereofand arranged to balance the same, a wheel guard supported at one end ofthe frame which has 120 side plates spaced apart only sufficiently tocarry a grinding wheel and its clamping flanges therebetween, anon-rotatable grinding wheel spindle removably supported wholly by theside plates, a handle on the guard end of the machine for guiding thewheel over the work, a grinding wheel rotatably mounted on said spindlebetween the side plates, a narrow clamping flange engaging each sideface of the wheel and provided with a narrow pulley groove close to theside of the wheel, a motor mounted on the opposite end of the frame andarranged to counterbalance the grinding wheel, pulleys on one end of themotor shaft having spaced narrow grooves aligned with the pulley groovesin the wheel flanges, and a 135 narrow belt oneach side of the grindingwheel connecting the motor pulleys with the clamping flange pulleys,said belts and pulleys being located within the planes defined by theside plates of the wheel guard, whereby obstruction of the 140 operatorsview of the work during grinding is minimized.

HOWARD W. DUNBAR.

